Tennis ace Serena Williams is using the traumatic experience following the birth of her daughter to advocate for better access to health care.

The sports star and her husband, Reddit co-founder Alexis Ohanian, welcomed daughter Alexis, Jr. in September, and last month Serena revealed in Vogue magazine her labor was a harrowing affair, as she required an emergency Cesarean section as her baby's heart rate "dove dangerously low during contractions."

As she recovered from the surgery, the new mother discovered she had small blood clots in her lungs, and she also required a further operation as her C-section wound opened, leading surgeons to discover a large hematoma - a collection of clotted blood, in her abdomen.

Williams has now written an opinion piece for CNN, insisting if she couldn't afford adequate medical care she may have died during her scary ordeal.

"I am so grateful I had access to such an incredible medical team of doctors and nurses at a hospital with state-of-the-art equipment," she writes. "They knew exactly how to handle this complicated turn of events. If it weren't for their professional care, I wouldn't be here today..."

Williams goes on to explain that women around the world lack the medical care they need and often die or lose babies during childbirth.

"Around the world, thousands of women struggle to give birth in the poorest countries," she writes. "When they have complications like mine, there are often no drugs, health facilities or doctors to save them. If they don't want to give birth at home, they have to travel great distances at the height of pregnancy. Before they even bring a new life into this world, the cards are already stacked against them..."

"Yet we are not doing our part," she continues. "We are not rising to the challenge to help the women of the world."

And she is urging readers to demand their political leaders, business executives, and bosses at nonprofit organizations take action.

"In doing so, you become part of this narrative - making sure that one day who you are or where you are from does not decide whether your baby gets to live or to die," she adds. "Together, we can make this change. Together, we can be the change."